[en] Plants are promising tools to produce complex recombinant proteins like antibodies. When host plants are grown on hydroponics, the production of recombinant proteins that are secreted by the roots ('rhizosecretion') greatly simplifies harvest and purification of the product, during whole plant life. However, proteases represent up to 10% of the naturally secreted proteins and are known to significantly decrease the yield of production by rhizosecretion. In this study, we analyzed the rhizosecreted proteases of Arabidopsis thaliana and Nicotiana tabacum. Total rhizosecreted proteins were recovered by salt extraction and the protease activity was assayed in vitro or by zymography. The relative contribution of major protease families to total activity was evaluated with specific inhibitors and revealed significant differences between the two species. The degradation capacity of the root-secreted proteases was further characterized against selected target proteins: BSA and human IgGs.
